Structure of Nanotubes Self-Assembled from a Monoamide Organogelator

Abstract

Some organic compounds are known to self-assemble into nanotubes in solutions, but the packing of the molecules into the walls of the tubes is known only in a very few cases. Herein, we study two compounds forming nanotubes in alkanes. They bear a secondary alkanamide chain linked to a benzoic acid propyl ester (HUB-3) or to a butyl ester (HUB-4). They gel alkanes for concentrations above 0.2 wt.%. The structures of these gels, studied by freeze fracture electron microscopy, exhibit nanotubes: for HUB-3 their external diameters are polydisperse with a mean value of 33.3 nm; for HUB-4, they are less disperse with a mean value of 25.6 nm. The structure of the gel was investigated by small- and wide-angle X-ray scattering. The evolution of the intensities show that the tubes are metastable and transit slowly toward crystals. The intensities of the tubes of HUB-4 feature up to six oscillations. The shape of the intensities proves the tubular structure of the aggregates, and gives a measurement of 20.6 nm for the outer diameters and 11.0 nm for the inner diameters. It also shows that the electron density in the wall of the tubes is heterogeneous and is well described by a model with three layers.

Gel-to-gel non-variant transition of an organogel caused by polymorphism from nanotubes to crystallites

“…These oscillations correspond to the same form factor as for nanotubes formed by HUB-4 in cyclohexane, a solvent closely related to trans-decalin. 26 Fits of the intensity with the same form factor yielded the same parameters within 1 nm, especially an external radius of 19 nm and internal radius of 12 nm. These nanotubes can be observed directly in cyclohexane by freeze fracture TEM (Fig.…”

“…In these gels, the aggregates are nanotubules as observed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). 26 Herein we show that for given temperatures and concentrations, they transform into aggregates of different shapes. We have studied the nature and the characteristics of this transformation by different techniques: quantitative VT-NMR, rheology and turbidimetry.…”

“…HUB-4 was synthesized following a described procedure. 26 trans-Decalin (TD) was purchased from TCI Chemicals and purified by filtration on a column of silica. Mechanical measurements.…”

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

“…In this Thematic Area, 56 articles have been published [ 48 , 64 , 104 , 108 , 110 , 124 , 195 , 252 , 253 , 254 , 255 , 256 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 264 , 265 , 266 , 267 , 268 , 269 , 270 , 271 , 272 , 273 , 274 , 275 , 276 , 277 , 278 , 279 , 280 , 281 , 282 , 283 , 284 , 285 , 286 , 287 , 288 , 289 , 290 , 291 , 292 , 293 , 294 , 295 , 296 , 297 , 298 , 299 , 300 ], an...…”

“…A more detailed examination shows that, in this direction, as well as in the previous ones, articles in which the objects of research are organic materials clearly prevail over articles in which the objects of research are inorganic materials (36 and 20, respectively). Wherein, the overwhelming majority of articles of the “organic” profile are, in one way or another, connected with the participation of the objects with a biological origin; these include [ 64 , 124 , 254 , 255 , 256 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 274 , 277 , 278 , 282 , 284 , 289 , 291 , 292 , 293 , 294 , 295 , 296 , 298 , 299 , 300 ] and the processes in abiogenic organic materials were considered only in [ 48 , 195 , 266 , 271 , 272 , 273 , 283 , 288 , 290 ]. The thematic focus of these works, as well as the chemical compounds studied in them, is also very diverse, and even a simple listing of them here is clearly beyond the scope of this article, too.…”